March 21, 1939
Dear Dr. Connell,
Mr. Larson has fixed the shunt valve very satisfactorily, and they are all lubricated properly now. The temporary piston did not happen to leak at all.
I hear of another explosion in New England this week. Your remarks on your work with intercoupling are most interesting, and I trust you will find a satisfactory solution soon. I still feel however, that common sense plays the biggest part in preventing explosions and that gas machines can never be made absolutely foolproof. Yesterday, we had a short circuit in the main floor plug directly beneath the operating table, while open drop ether was being given (for student instruction). Fortunately there was no fire, but why put floor plugs in that location? The hospital construction people are working hard on this problem, and have numerous improvements up their sleeves.
As for your questions; yes, there was a metal neck on the Heidbrink bag, and I believe the touching of this piece to the machine was the source of the spark. Why could not charge accumulate at the attachment of the rubber bag, and the metal neck, and be the actual source of difference in potential?
The Stratosphere, and table models are all behaving well now, and after a breathing spell we shall consider replacing some other machines.
Sincerely,
Virginia Apgar, M.D.